排序方式: 共有134条查询结果,搜索用时 15 毫秒
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石墨二炔是由sp和sp2杂化的碳原子构成的新的碳同素异形体。由于石墨二炔具有独特的拓扑结构和电子结构、较高的电荷迁移率及优异的电子传输性能,使其与其他材料相互作用,可表现出独特的电子转移增强特性。本文基于石墨二炔的电子转移增强特性,概述了石墨二炔及其电子转移增强特性的最新研究进展,包括金属氧化物/石墨二炔、金属纳米颗粒/石墨二炔、聚合物/石墨二炔以及染料分子/石墨二炔等多种石墨二炔基材料。本文从理论和实验研究两个方面详细阐述了石墨二炔的电子转移增强特性、石墨二炔与不同材料的相互作用以及相关的应用。希望该综述能对石墨炔化学的发展起到一定的积极作用。 相似文献
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WANG Qi YANG Xiaohui JIANG Yanqiu HUO Hang LI Defeng LIN Kaifeng XU Xianzhu 《高等学校化学研究》2018,34(1):13-18
Amino-functionalized porous SiO2 beads with a diameter of 200—800 μm(PSB-NH2) have been successfully synthesized by grafting 3-aminopropyl-triethoxysilane onto meso/macroporous silica beads(PSB), in which the PSB was prepared by hydrothermal synthetic method with a porous hard template anion-exchange resin. The as-prepared materials were characterized by means of nitrogen sorption and transmission electron micrographs(TEM), showing the presence of 3D interconnected and continuous large mesopores and macropores inside. The beads were used to catalyze Knoevenagel condensation and proved to be highly active and selective due to the high accessibility of the reactants to the amino groups via the continuous 3D meso/macopores. Notably, such material in bead format facilitates the extremely straightforward separation from reaction solution without any centrifugation or filtration. Moreover, PSB-NH2 proved to be a stable catalyst via leaching experiment test, and can be easily recovered and reused without significant loss of activity in successive catalytic cycles. 相似文献
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利用向环金属配体的C-Ir键的对位进行苯基取代这一结构修饰策略,成功合成了两种新型铱(III)配合物(3PhNbt)2Ir(acac)和(3OMePhNbt)2Ir(acac).相较其橙光发射的母体化合物(Nbt)2Ir(acac),两个目标化合物的抗结晶性、非晶态热稳定性及溶解性均有显著提高,其磷光发射带也发生了5~10 nm的红移.以(3PhNbt)2Ir(acac)和(3OMePhNbt)2Ir(acac)为发光客体材料所制备的单层溶液加工电致红光器件,其最大发光亮度分别为1830 cd·m-2和6630 cd·m-2,最大电流效率分别为2.4 cd·A-1和8.7 cd·A-1,CIE1931色坐标分别为(0.61,0.39)和(0.62,0.38).相比之下,以母体化合物(Nbt)2Ir(acac)为发光客体材料所制备的参比器件,其最大发光亮度则为1620 cd·m-2,最大电流效率仅为1.5 cd·A-1,CIE1931色坐标为(0.59,0.41).上述研究结果表明:向C-Ir键对位进行苯基修饰可以在提高铱(III)配合物的可溶液加工性能的同时,获得更为红移的电致发光波长,是一种简单而有效的红光铱(III)配合物的分子设计策略. 相似文献
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Submicrometer-sized tin-containing MCM-41 particles with a size of several hundred nanometers(Sn-MCM-41/SMPs) were rapidly prepared with tin chloride as tin source and tetraethyl orthosilicate as silicon source via a dilute solution route in sodium hydroxide medium at room temperature. The characterization results show the highly ordered hexagonal mesopores and tetrahedral Sn species in Sn-MCM-41/SMPs. The material proved to be active and selective for Baeyer-Villiger oxidation of adamantanone with aqueous H2O2. Notably, Sn-MCM-41/ SMPs displayed a higher initial reaction rate and turnover number(TON) than common micrometer-sized Sn-MCM-41 large particles(Sn-MCM-41/LPs), mainly attributed to the accelerated diffusion of the reactants and enhanced accessibility to the catalytic Sn species via shorter mesopore channels in Sn-MCM-41/SMPs. Furthermore, Sn-MCM-41/SMPs could be reused without the loss of activity after five runs, indicating that Sn active sites in the submicrometer-sized particles are remarkably stable. The study shows that decreasing particle size of Sn-MCM-41 in submicrometer scale is an effective way to achieve catalysts for Baeyer-Villiger oxidations with improved catalytic performance. 相似文献
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Wu K Zhu H Liu Z Rodríguez-Córdoba W Lian T 《Journal of the American Chemical Society》2012,134(25):10337-10340
Colloidal semiconductor-metal nanoheterostructures that combine the light-harvesting ability of semiconductor nanocrystals with the catalytic activity of small metal nanoparticles show promising applications for photocatalysis, including light-driven H(2) production. The exciton in the semiconductor domain can be quenched by electron-, hole-, and energy transfer to the metal particle, and the competition between these processes determines the photocatalytic efficiency of these materials. Using ultrafast transient absorption spectroscopy, we show that, in CdS-Pt heterostructures consisting of a CdS nanorod with a Pt nanoparticle at one end, the excitons in the CdS domain dissociate by ultrafast electron transfer (with a half-life of ~3.4 ps) to the Pt. The charge separated state is surprisingly long-lived (with a half-life of ~1.2 ± 0.6 μs) due to the trapping of holes in CdS. The asymmetry in the charge separation and recombination times is believed to be the key feature that enables the accumulation of the transferred electrons in the Pt tip and photocatalysis in the presence of sacrificial hole acceptors. 相似文献
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研究了一类非线性薛定谔型方程,描述了光波在光折射晶体中的传播.首先构造了该模型整体弱的吸引子,然后通过能量方程的精确分析,证明整体弱吸引子实际为系统整体强吸引子.最后给出了整体吸引子的分形维数和Hausdorff维数的上界估计. 相似文献
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三维非稳态热传导逆问题反演算法研究 总被引:3,自引:0,他引:3
利用表面温度测量来反演热传导方程中的热源项是一类典型的热传导逆问题,在采用有限体积法对三维非稳态热传导问题进行数值求解的基础上,将该热传导逆问题转化为优化问题,建立了伴随方程法和共轭梯度法这两类反演算法. 采用这两类算法对一个典型算例的计算结果表明:建立的两类反演算法是有效的,具有较好的抗噪性能. 此外,对反演算法中计算收敛准则的选取进行了较深入的分析,结果表明,由于热传导逆问题的不适定性,优化过程中目标函数值越小并不意味着反演结果与真值更为接近,可以通过设定合适的收敛准则来模拟正则化项的作用,克服不适定性的影响. 相似文献
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Tao Zhu Hong Zhang Sijie Li Kaifeng Wu Yibing Yin Xuemei Zhang 《Experimental & molecular medicine》2022,54(5):601
Leukemia is caused by the malignant clonal expansion of hematopoietic stem cells, and in adults, the most common type of leukemia is acute myeloid leukemia (AML). Autophagy inhibitors are often used in preclinical and clinical models in leukemia therapy. However, clinically available autophagy inhibitors and their efficacy are very limited. More effective and safer autophagy inhibitors are urgently needed for leukemia therapy. In a previous study, we showed that ΔA146Ply, a mutant of pneumolysin that lacks hemolytic activity, inhibited autophagy of triple-negative breast cancer cells by activating mannose receptor (MR) and toll-like receptor 4 (TLR4) and that tumor-bearing mice tolerated ΔA146Ply well. Whether this agent affects AML cells expressing TLR4 and MR and the related mechanisms remain to be determined. In this study, we found that ΔA146Ply inhibited autophagy and induced apoptosis in AML cells. A mechanistic study showed that ΔA146Ply inhibited autophagy by activating mammalian target of rapamycin signaling and induced apoptosis by inhibiting autophagy. ΔA146Ply also inhibited autophagy and induced apoptosis in a mouse model of AML. Furthermore, the combination of ΔA146Ply and chloroquine synergistically inhibited autophagy and induced apoptosis in vitro and in vivo. Overall, this study provides an alternative effective autophagy inhibitor that may be used for leukemia therapy.Subject terms: Translational research, Acute myeloid leukaemia 相似文献
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Xiaohui Duan Mina Zhang Huan Du Xiu Gu Caihong Bai Liuqiang Zhang Kaixian Chen Kaifeng Hu Yiming Li 《Molecules (Basel, Switzerland)》2022,27(15)
Scrophulariae Radix (SR) is one of the oldest and most frequently used Chinese herbs for oriental medicine in China. Before clinical use, the SR should be processed using different methods after harvest, such as steaming, “sweating”, and traditional fire-drying. In order to investigate the difference in chemical constituents using different processing methods, the two-dimensional (2D) 1H-13C heteronuclear single quantum correlation (1H-13C HSQC)-based metabolomics approach was applied to extensively characterize the difference in the chemical components in the extracts of SR processed using different processing methods. In total, 20 compounds were identified as potential chemical markers that changed significantly with different steaming durations. Seven compounds can be used as potential chemical markers to differentiate processing by sweating, hot-air drying, and steaming for 4 h. These findings could elucidate the change of chemical constituents of the processed SR and provide a guide for the processing. In addition, our protocol may represent a general approach to characterizing chemical compounds of traditional Chinese medicine (TCM) and therefore might be considered as a promising approach to exploring the scientific basis of traditional processing of TCM. 相似文献